A total of 26 strains of avian pathogenic
Escherichia coli isolated from broiler chickens with colibacillosis were investigated for the pathological feature β-lactamase productivities, serotypes and molecular epidemiological characteristics including sequence types (STs) analyzed using multilocus sequence typing (MLST) and phylogenetic groups. The most prevalent characteristics were O2:H-, ST95, and phylogenetic group B2; and O25:H4, ST131, and B2 (four strains each). Fifteen (58%) of the 26 isolates possessed β-lactamase gene (s) including
blaCMY-2 (nine strains),
blaTEM-1 (seven strains),
blaCTX-M-15 (one strain),
blaCTX-M-2 (two strains), and
blaSHV-2 (one strain). In the β-lactamase gene-positive strains, the prevalence rate of the three virulence-associated genes (VAGs),
iss,
iucD, and
papC, was significantly high (
P<0.05), and the prevalence of the other five VAGs (
astA,
irp2,
tsh,
vat, and
cva/cvi) tended to be high compared to the β-lactamase gene-negative strains. These results suggested that the β-lactamase gene and VAGs were likely to be conserved in
E. coli that caused avian colibacillosis. It is necessary to observe the diffusion of avian pathogenic
E. coli, because we found
E. coli strains possessing extended spectrum β-lactamase (ESBL) genes (i.e.
blaCTX-M-15,
blaCTX-M-2,
blaSHV-2) and O25:H4 (ST131 and B2) strains, which were the major type of ESBL-producing
E. coli isolated from patients.
View full abstract